Filter cartridge

ABSTRACT

A filter cartridge ( 10 ), in this case comprising an injection moulded cylindrical plastics body ( 11 ) having spaced anti-tracking ribs ( 12 ) which are disposed unevenly along the inner surface ( 13 ) of the hollow body ( 11 ). First and second paper rolls as filter elements ( 14  and  15 ) have been pushed under compression into the hollow body ( 11 ) and are separated by spacer means ( 16 ) located centrally within the hollow body ( 11 ). Spacer means ( 16 ) is made from two separate spacers ( 18 ) which are generally made in the form of a spoked wheel type arrangement. Each spacer ( 18 ) comprises an outer ring ( 19 ) and an inner ring ( 20 ), the inner ring ( 20 ) has four apertures or recesses ( 21 ) on its top and offset by 45 degrees equally on its opposite side are four more equally spaced apertures ( 21 ) making a total of eight, the apertures provide flow through passages ( 21 ) through the inner ring ( 20 ), plastic connector portions ( 22 ) extend radially between the rings ( 19  and  20 ).

TECHNICAL FIELD OF THE INVENTION

[0001] THIS INVENTION relates to a filter cartridge and in particular,but not limited to, a filter cartridge suitable for filtering oil orfuel.

BACKGROUND TO THE INVENTION

[0002] Filters are known that employ an outer filter body holdingdisposable filter cartridges, the outer body usually has a cylindricalhousing and a cap, a coaxial return pipe usually has a threaded end andthe cap screws onto the threaded end to clamp the cartridges inoperative position in the housing. Liquid flows though an inlet, throughfilter media in the cartridges and out through the return pipe. Spentcartridges are simply exchanged with new ones. Typical cartridges areknown that are made from a paper roll held in a plastics or metalcylinder. An example is described in WO/0037232. There are variousalternative constructions and flow modalities used.

[0003] European patent application No. P 0 556 506A1 describes a modularfilter system consisting of cartridges made from a tightly wrapped paperfilter media retained in a plastic casing. The plastic casing hasintegrally formed grate-like configuration on its top and bottomsurfaces to allow fluid to enter an exit the filter. The casing is alsodimensioned to closely surround the paper media. The filter cartridgesare stackable within the filter housing which can retain a plurality ofcartridges thereby increasing the capacity of the filter. Each casing ismade from identical top and bottom halves where the cylindrical wallsclip together around the paper roll. When two cartridges are used thegrid like top of one cartridge a butts the grid-like bottom of the otherso that liquid flows from one cartridge to the next in series. Thusliquid flows one way, from one end only and is recovered out the otherend. The central pipe in this case is an inlet pipe rather than a returnpipe.

[0004] Other arrangements are known where liquid flows simultaneouslyinto the filter in opposite directions and is recovered centrally, seefor example Australian Patent 729523 and U.S. Pat. No. 4,792,397.

[0005] Australian Patent 729523 and WO/0037232 describe an injectionmoulded filter cartridge filled with a paper roll filter media. Unlikethe cartridge of European patent application No. P 0 556 506A1, thecartridge is open ended and does not employ grate-like ends. This allowsa press to be used to insert paper rolls under pressure. In onecartridge opposite ends of the cartridge are completely open so thecartridge is effectively a tube with two back-to-back paper rollsseparated by gauze providing a return flow path. The paper rolls have acentral bore made of cardboard for a return pipe. Thus when thecartridge is clamped inside a filter container liquid flows from aninlet in the container in both ends of the cartridge, through the paperrolls and is recovered by flowing out the ends of the paper rollsthrough a common return path formed by the gauze to the central returnpipe. The gauze separates the confronting ends of the rolls and providesa flow path for the filtered liquid. Gauze is also used in thearrangement of Australian patent 659793 to separate two paper rolls in ametal cannister.

[0006] In U.S. Pat. No. 4,792,397 back-to-back paper rolls are used in asimilar arrangement Australian Patent 729523 and WO/0037232 exceptinstead of gauze being used to separate the rolls U.S. Pat. No.4,792,397 uses a specially made fluid collector between the rolls. Thefluid collector has closely spaced concentric ridges projecting fromopposite sides of a substantially flat portion, pressure equalisationholes pass through the flat portion. The ridges push into the paperrolls on opposite sides of the collectors. Gaps in each ridge allowsradial return flow to the central return pipe.

[0007] In Australian patent 650176 a metal canister is provided with endwall depressions to improve radial return flow. In Australian patentapplication 59243/00 a fluid collector is provided in an end wall of thehousing, the fluid collector has lands in the form of sectors of acircle separated by radial flow passages.

[0008] The prevailing design criteria adopted in all these instances isto support the paper across its ends in an effort to maintain the returnflow and minimise blockages that might impede flow as the papercollapses. Since the filters are pressurised as the filter media agesand becomes loaded it may distort in the region of the return flowleading to blockages. The gauze may become depressed by the paper beingforced across the gap. Thus in the above examples it is usual to providea substantial amount of support at the end of the paper roll with fluidcollectors with relatively large flow paths being preferred to wiregauze.

[0009] The present invention adopts a completely different approach tothe problem of supporting the roll while maintaining greater efficiencyof return flow across the filter.

OUTLINE OF THE INVENTION

[0010] In one aspect there is provided filter cartridge having a hollowouter body, a filter element having an inlet end and an outlet end andbeing held in the outer body and there being a return flow passageadjacent the outlet end, spacer means defining the return flow passage,characterised in that the spacer means comprises an axially extendingscreen support member and a screen supported on the screen supportmember, the screen being disposed between the filter element and thescreen support member for flow of filtrate though the screen into thereturn flow passage.

[0011] Preferably, the hollow outer body has openings at each end, apair of said filter elements being held in longitudinally spacedrelation in the outer body, said spacer means being disposed between therespective filter elements, the spacer means having oppositelongitudinally spaced apart screen supports, and a respective saidscreen being supported on said spaced apart screen supports, each screenbeing disposed between a respective filter element and the screensupport for flow of filtrate though the screens into the return flowpassage.

[0012] Preferably, the spacer means comprises radially spaced inner andouter ring members held apart by circumferentially spaced radiallyextending vanes connecting the ring members together, the vanesextending longitudinally and having opposite edges forming open sectorsbetween the vanes, the edges of the vanes being said screen support andproviding the return flow passage between the vanes, the inner ringhaving flow through passage means communicating with the return flowpassage.

[0013] Preferably, the spacer means comprises two separate spacer meanswith circumferentially offset sets of vanes.

[0014] Preferably, the spacer means is wheel-like having a central huband an outer rim connected by circumferentially spaced radial spokemeans, the central hub having flow through passage means enabling flowof filtrate from a region adjacent the radial spoke means to a centralpassage means in the hub. Preferably, the spacer means comprises twoidentical spacers slid into the hollow body and located centrallybetween longitudinally spaced circumferentially extending anti-trackingribs in an inner wall of the hollow body.

[0015] Preferably, the filter elements are paper rolls and the hollowbody includes spaced ribs projecting from an inner wall thereof andimpinging upon the filter elements.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order that the present invention can be more readilyunderstood and be put into practical effect, reference will now be madeto the accompanying drawings which illustrate a preferred embodiment ofthe invention and wherein:

[0017]FIG. 1 is a longitudinal section through a filter elementaccording to the present invention, the filter element being cylindricalin transverse cross section;

[0018]FIGS. 2 and 3 are respective section and plan views of a typicalspacer two such spacers being employed in the FIG. 1 embodiment;

[0019]FIGS. 4 and 5 are respective side and plan views of a mesh screensuitable for use with the spacer of FIGS. 2 and 3; and

[0020]FIG. 6 is a part section showing the structure of the mesh screenof FIGS. 4 and 5.

METHOD OF PERFORMANCE

[0021] Referring to the drawings and initially to FIG. 1 there isillustrated a filter cartridge 10, in this case comprising an injectionmoulded cylindrical plastics body 11 having spaced anti-tracking ribs 12which are disposed unevenly along the inner surface 13 of the hollowbody 11. First and second paper rolls as filter elements 14 and 15 havebeen pushed under compression into the hollow body 11 and are separatedby spacer means 16 located centrally within the hollow body 11.

[0022] Each of the paper rolls 14 and 15 include a central cylindricalcore 16 so that a return pipe (not shown) can be inserted through thecartridge when the cartridge is clamped within a housing (not shown).Fluid flows in the direction of the arrows through the filters back andradially through the spacer 16 and through apertures 17 so that filtratetravels to the return pipe (not shown).

[0023] In the illustrated embodiment the spacer means 16 is made fromtwo separate spacers 18 which are generally made in the form of a spokedwheel type arrangement as illustrated in FIGS. 2 and 3. Two spacers areused because a single spacer of the same size would be too rigid to beinserted due to the ribs 12.

[0024] Referring to FIGS. 2 and 3 the spacer 18 comprises an outer ring19 and an inner ring 20, the inner ring 20 has four apertures orrecesses 21 on its top and offset by 45 degrees equally on its oppositeside are four more equally spaced apertures 21 making a total of eight,the apertures provide flow through passages 21 through the inner ring20, plastic connector portions 22 extend radially between the rings 19and 20.

[0025] Since the outer body 11 is made from a relatively rigid plasticsmaterial as are the spacers 18, the dimensions of the spacers 18 areselected so that the spacers 18 can be pushed into position over theridges 12.

[0026] Mesh screens 22 are placed in position atop the spacers 18 priorto insertion of the paper filter elements 14 and 15.

[0027] Preferred mesh screens are illustrated in FIGS. 4, 5 and 6, themesh screens include tapered screen elements 23. The mesh screen is, inthis embodiment, preferably injection moulded and formed with marginaledge sections 25 adjacent the central opening 24 and outer peripheralmarginal edge sections 26 formed so as to inhibit any fraying that mightresult in portions of the mesh screen being dislodged into the filtrate.

[0028] Whilst the above has been given by way of illustrative example ofthe present invention many variations and modifications thereto will beapparent to those skilled in the art without departing from the broadambit and scope of the invention as set out in the appended claims.

1. A filter cartridge having a hollow outer body, a filter elementhaving an inlet end and an outlet end and being held in the outer bodyand there being a return flow passage adjacent the outlet end, spacermeans defining the return flow passage, characterised in that the spacermeans comprises an axially extending screen support member and a screensupported on the screen support member, the screen being disposedbetween the filter element and the screen support member for flow offiltrate though the screen into the return flow passage.
 2. A filtercartridge according to claim 1 wherein the hollow outer body hasopenings at each end, a pair of said filter elements being held inlongitudinally spaced relation in the outer body, said spacer meansbeing disposed between the respective filter elements, the spacer meanshaving opposite longitudinally spaced apart screen supports, and arespective said screen being supported on said spaced apart screensupports, each screen being disposed between a respective filter elementand the screen support for flow of filtrate though the screens into thereturn flow passage.
 3. A filter cartridge according to claim 1 whereinthe spacer means comprises radially spaced inner and outer ring membersheld apart by circumferentially spaced radially extending vanesconnecting the ring members together, the vanes extending longitudinallyand having opposite edges forming open sectors between the vanes, theedges of the vanes being said screen support and providing the returnflow passage between the vanes, the inner ring having flow throughpassage means communicating with the return flow passage.
 4. A filtercartridge according to claim 1 wherein the spacer means comprises twoseparate spacer means with circumferentially offset sets of vanes.
 5. Afilter cartridge according to claim 1 wherein the spacer means iswheel-like having a central hub and an outer rim connected bycircumferentially spaced radial spoke means, the central hub having flowthrough passage means enabling flow of filtrate from a region adjacentthe radial spoke means to a central passage means in the hub.
 6. Afilter cartridge according to claim 1 wherein the spacer means comprisestwo identical spacers slid into the hollow body and located centrallybetween longitudinally spaced circumferentially extending anti-trackingribs in an inner wall of the hollow body.
 7. A filter cartridgeaccording to claim 1 wherein the filter elements are paper rolls and thehollow body includes spaced ribs projecting from an inner wall thereofand impinging upon the filter elements.
 8. A filter cartridge accordingto claim 1 wherein the hollow outer body has openings at each end, apair of said filter elements being held in longitudinally spacedrelation in the outer body, said spacer means being disposed between therespective filter elements, the spacer means having oppositelongitudinally spaced apart screen supports, and a respective saidscreen being supported on said spaced apart screen supports, each screenbeing disposed between a respective filter element and the screensupport for flow of filtrate though the screens into the return flowpassage, the spacer means comprises radially spaced inner and outer ringmembers held apart by circumferentially spaced radially extending vanesconnecting the ring members together, the vanes extending longitudinallyand having opposite edges forming open sectors between the vanes, theedges of the vanes being said screen supports and providing the returnflow passage between the vanes, the inner ring having flow throughpassage means communicating with the return flow passage.
 9. A filtercartridge according to claim 1 wherein the hollow outer body hasopenings at each end, a pair of said filter elements being held inlongitudinally spaced relation in the outer body, said spacer meansbeing disposed between the respective filter elements, the spacer meanshaving opposite longitudinally spaced apart screen supports, and arespective said screen being supported on said spaced apart screensupports, each screen being disposed between a respective filter elementand the screen support for flow of filtrate though the screens into thereturn flow passage and the spacer means comprises two separate spacermeans with circumferentially offset sets of vanes.
 10. A filtercartridge according to claim 1 wherein the hollow outer body hasopenings at each end, a pair of said filter elements being held inlongitudinally spaced relation in the outer body, said spacer meansbeing disposed between the respective filter elements, the spacer meanshaving opposite longitudinally spaced apart screen supports, and arespective said screen being supported on said spaced apart screensupports, each screen being disposed between a respective filter elementand the screen support for flow of filtrate though the screens into thereturn flow passage, the spacer means is wheel-like having a central huband an outer rim connected by circumferentially spaced radial spokemeans, the central hub having flow through passage means enabling flowof filtrate from a region adjacent the radial spoke means to a centralpassage means in the hub.
 11. A filter cartridge according to claim 1wherein the hollow outer body has openings at each end, a pair of saidfilter elements being held in longitudinally spaced relation in theouter body, said spacer means being disposed between the respectivefilter elements, the spacer means having opposite longitudinally spacedapart screen supports, and a respective said screen being supported onsaid spaced apart screen supports, each screen being disposed between arespective filter element and the screen support for flow of filtratethough the screens into the return flow passage, the spacer meanscomprises two identical spacers slid into the hollow body and locatedcentrally between longitudinally spaced circumferentially extendinganti-tracking ribs in an inner wall of the hollow body.
 12. A filtercartridge according to claim 1 wherein the hollow outer body hasopenings at each end, a pair of said filter elements being held inlongitudinally spaced relation in the outer body, said spacer meansbeing disposed between the respective filter elements, the spacer meanshaving opposite longitudinally spaced apart screen supports, and arespective said screen being supported on said spaced apart screensupports, each screen being disposed between a respective filter elementand the screen support for flow of filtrate though the screens into thereturn flow passage and the filter elements are paper rolls and thehollow body includes spaced ribs projecting from an inner wall thereofand impinging upon the filter elements.
 13. A filter cartridge accordingto claim 1 wherein the spacer means comprises the two separate spacermeans with circumferentially offset sets of vanes, each spacer meanscomprising radially spaced inner and outer ring members held apart bycircumferentially spaced radially extending vanes connecting the ringmembers together, the vanes extending longitudinally and having oppositeedges forming open sectors between the vanes, the edges of the vanesbeing said screen support and providing the return flow passage betweenthe vanes, the inner ring having flow through passage meanscommunicating with the return flow passage.
 14. A filter cartridgeaccording to claim 1 wherein the spacer means comprises two identicalspacers slid into the hollow body and located centrally betweenlongitudinally spaced circumferentially extending anti-tracking ribs inan inner wall of the hollow body, each spacer means comprises radiallyspaced inner and outer ring members held apart by circumferentiallyspaced radially extending vanes connecting the ring members together,the vanes extending longitudinally and having opposite edges formingopen sectors between the vanes, the edges of the vanes being said screensupport and providing the return flow passage between the vanes, theinner ring having flow through passage means communicating with thereturn flow passage.
 15. A filter cartridge according to claim 1 whereinthe spacer means comprises radially spaced inner and outer ring membersheld apart by circumferentially spaced radially extending vanesconnecting the ring members together, the vanes extending longitudinallyand having opposite edges forming open sectors between the vanes, theedges of the vanes being said screen support and providing the returnflow passage between the vanes, the inner ring having flow throughpassage means communicating with the return flow passage and the filterelements are paper rolls and the hollow body includes spaced ribsprojecting from an inner wall thereof and impinging upon the filterelements.
 16. A filter cartridge according to claim 1 wherein the spacermeans comprises two separate spacer means with circumferentially offsetsets of vanes, each spacer means is wheel-like having a central hub andan outer rim connected by circumferentially spaced radial spoke means,the central hub having flow through passage means enabling flow offiltrate from a region adjacent the radial spoke means to a centralpassage means in the hub.
 17. A filter cartridge according to claim 1wherein the spacer means comprises two separate spacer means withcircumferentially offset sets of vanes and the filter elements are paperrolls and the hollow body includes spaced ribs projecting from an innerwall thereof and impinging upon the filter elements.